Is it actually anachronistic? There's a number of verbs that follow a similar pattern (leant/leaned, learnt/learned, dreamed/dreamt, kneeled/knelt, spoiled/spoilt etc.) and I was taught British English uses the verbs irregular versions of these verbs (i.e. the ones that end in 't') while American English uses the regular version.

Leant (pronounced 'lent' in case any Americans are unclear on that) is still current in British English and at least some former colonies like Australia. It's like 'meant', as in the past participle of 'mean', which is still used in the US rather than 'meaned', which sounds really weird.

You are entering the vicinity of an area adjacent to a location. The kind of place where there might be a monster, or some kind of weird mirror. These are just examples; it could also be something much better. Prepare to enter: The Scary Door.

British English uses 'leant', 'learnt', 'slept', 'burnt', 'dreamt'. A lot of the Anglosphere follows the US English convention of past participles taking an '-ed' suffix, it makes sense. British English (and the Anglosphere using British English) use the older '-t' suffix for certain verbs, although there are probably more examples of the '-ed' suffix today. New verbs get '-ed' by default.

Do they actually spell it that way!? I was under the impression it was a quirk of the accent ('-t' suffix lends itself to a glottal stop and thus contributes to the lyrical flowing quality typically attributed to the "Southern Drawl").

Well today I learned.

The British English spellings are dying out, a lot of European Countries are taught American English (and an overwhelming majority of European Countries have excellent English speakers). With the rise of the Internet I feel it's very likely British English will fall in line with the '-ed' suffix within the next decade. More past participles of ours already follow this convention.

As someone who writes a lot of technical documentation (and has an American wife) I find myself writing in American English unless I happen to know the person I'm writing to is a Brit, or if I'm in a British-orientated area of the web.

Yeah, but if you have one that gets a lot of use the paper dust builds up on the sensor and no one in the office cares enough to clean it and the motherfucker is always running when it's on. Makes it more like a wood chipper. Tuck your tie into your shirt before use.